Hydraulic roll drive means for briquetters and compactors

ABSTRACT

An apparatus for agglomerating particulate material as in a briquetting or compacting construction. The improvement of the invention relates to drive means for the agglomerating rolls. The drive means include individual hydraulic motors for the rolls with separate or common pumps being employed in conjunction with the hydraulic motors. Detecting means may be connected to at least one of the roll shafts for thereby determining the relative angular positions of the rolls mounted on the shaft. Control means are operated by the detecting means so that momentary variations in the speeds of rotation of the rolls can be made to synchronize the rolls. The control system preferably comprises an automatic quick response arrangement so that the rolls are maintained at proper synchronization throughout the agglomerating operation.

United States Patent 11 1 Harris HYDRAULIC ROLL DRIVE MEANS FORBRIQUETTERS AND COMPACTORS [75] Inventor: Leroy S. Harris, RollingMeadows,

[52] [1.8. CI. 60/97 E, 60/420, 91/171,

, v 425/168 [51] Int. Cl. FlSb 11/22 [58] Field of Search 60/97 E, 97 S,420;

Primary Examiner-Edgar W. Geoghegan Attorney-McDougall, Hersh & Scott 7ABSTRACT vidual hydraulic motors for the rolls with separate or commonpumps being employed in conjunction with the hydraulic motors. Detectingmeans may be connected to at least one of the roll shafts for therebydetermining the relative angular positions of the rolls mounted on theshaft. Control means are operated by [56] References Cited the detectingmeans so that momentary variations in UNITED STATES PATENTS the speedsof rotation of the rolls can be made to synchronize the rolls. Thecontrol system preferably comg 2 g 3 prises an automatic quick responsearrangement so OWCI' 3,550.205 12/1970 Guseman et al. 425/168 x that themus are mamtamefi at Synchmmzam throughout the agglomeratmg operatlon.FOREIGN PATENTS OR APPLICATIONS 845,054 8/1960 Great Britain 60/97 EClam, 5 D'awmg figures f0 55 14 ,i 30 i ROLL W 1 62E ROLL XE a4 4 12 50/VARIABLE DISPLACEMENT 46 HYDRAULIC PUMPS 3a 1 EL ECT MOTOR ELECTRICALcommons/e 6 NULL SIGNAL BALANCE TYPE. 1

LELECTRIC SIGNAL com arator 52 i0 .F IGZZ VARIABLE 'DISPLACEME HYDRALILIC PUM PS EL ECT MOTOR ELECTRICAL coumouelz NULL SIGNAL BALANCE TYPECOMPARATOR 52 v E LECTRI C SIGNA L v HYDRA'ULIC EL -n2 K2 R0 L M T RMOTOR HYDRAULIC ELECTRIC R0 L L M01012 MOTOR PAIENIEIIIII I W 4 3. 765.1 73 I SHEET F 2 I FIGA 5 26 I HY RA ROLL 2 72 K74 ELECITQIC MOTOR ROLLHYDRAULIC I moTqIz (12 76 I FIG. 4 78 DIFFERENTIAL DIFFERENTIAL TRAIIsFoRMEIa TRANSFORMER numb /NULL BALANCE (D INDICATORAND CONTROLLER L88F! G, 5 I

ll-REVOLUTION A 7 I l 0 90 I 270 360 I SIGNAL FROM SIGNAL FROM "A"oII=I=. TRANSFORMER "B' DlFF. TRANSFORMER 1 HYDRAULIC ROLL DRIVE MEANSFOR BRIQUETTERS AND COMPACTORS This invention is directed to drive meansfor agglomerating constructions. The invention is particularly concernedwith constructions such as briquetters and compactors which employ apair of rolls, and which have means for feeding particulate materialbetween the rolls. The rolls are mounted so that high pressure isapplied to the particulate material passing between the rolls.

Briquetters and compactors have commonly employed speed reducers inconjunction with roll drive systems. Speed reducers perform the desiredfunction of controlling various drive characteristics; however, inbriquetting and compacting operations, the speed reducers are subjectedto excessive gear loading whereby gear wear becomes a significantproblem. Excessive loading is experienced by speed reducer internalswhen the torque on one roll varies from O to 100 percent in asubstantially instantaneous fashion. The sharp loading causes torsionalflexing in the internals with excessive wear and consequent expense tothe customer A being the result. These problems occur in rather regularfashion on any large units used for briquetting and compacting purposes.

In the case of briquetting machines, the rolls may define opposedpockets whereby the particulate material will be formed into briquets.Flat sheets or other compacted forms can also be produced withconstructions of this type. It has been found that the quality of abriquet or other compacted article depends to some extent on the natureof the forces which are applied during an agglomerating operation. In anideal situation, the forces applied are substantially all compressiveforces; however, various factors can lead to differential stressincluding shear and tensile forces. Where an ideal force distributiondoes not occur, the agglomerated product may contain cracks or otherdefects.

In briquetting machines, it has been recognized that the best forcedistribution during agglomerating is achieved when the agglomeratingrolls operate at substantially the same speed with the pockets thereofbeing in an aligned relationship during briquet formation. Speedreducers have been employed so that the operation of one roll can besynchronized with the operation of another roll. As indicated, however,the speed reducers create other problems since their operation requiresa rather substantial application of force to gears which leads toexcessive loading and to gear wear.

It is a general object of this invention to provide an improvedhydraulic drive system for briquetting and compacting equipment.

It is a more specific object of this invention to provide improved drivearrangements for the rolls of briquetting and compacting machineswhereby roll synchronization can be maintained without requiringexcessive loading and without incurring excessive wear of componentparts.

These and other objects of this invention will appear hereinafter, andfor purposes of illustration, but not of limitation, specificembodiments of the invention are shown in the accompanying drawings inwhich:

FIG. 1 is a diagrammatic illustration ofa briquetting constructioncharacterized by the features of this invention;

FIG. 2 is a schematic illustration of a slightly modified version of theinvention shown in FIG. 1;

FIG. 3 is a schematic illustration of a further modified version oftheinvention;

FIG. 4 is a detailed schematic illustration of a combined roll positiondetecting and control system which may be utilized in the practice ofthe invention; and,

FIG. 5 is a graphical illustration of the operating characteristics ofthe detecting means shown in FIG. 4.

The apparatus of the invention relates to a briquetting and compactingconstruction or any other similar apparatus employed for agglomeratingparticulate material. Particularly included are constructions whichinclude a pair of agglomerating rolls along with means for feedingparticulate material through the rolls whereby briquets, compactedsheets, or similar products can be formed.

The invention is particularly concerned with improved drive means forthe agglomerating rolls. Specifically, the drive means consist of a pairof hydraulic motors with one motor being connected to each roll. Pumpmeans are employed for operating the hydraulic motors, and a separateelectric motor or the like is utilized for operating the pump means.

The structures of the invention may include a detecting and controlsystem utilized for achieving momentary variations in the speed ofrotation of the agglomerating rolls so that roll synchronization can bemaintained throughout the agglomerating operation. The detecting meanspreferably comprise a pair of signal generators connected directly tothe rotating shafts carrying the agglomerating rolls. The signalsgenerated are fed to a comparator, and if the agglomerating rolls are inproper synchronization, then there will be no net signal observed by thecomparator. On the other hand, if there is a difference in the angularpositions of the rolls, then an output from the comparator will serve tomomentarily vary the roll speeds to bring the rolls back to propersynchronization. By providing a quick response system, the agglomeratingrolls can be maintained in substantially constant synchronizationthereby providing a uniform and satisfactory production.

FIG. 1 illustrates a system incorporating various aspects of the instantinvention. In this system, a pair of briquetting rolls l0 and 12 aremounted on supporting shafts 14 and 16 which are in turn supported bybearings l8 and 20. The shafts are connected through couplings 22 and 24to hydraulic drive motors 26 and 28.

The hydraulic drive motor 26 is connected through lines 30 and 32 to avariable displacement hydraulic pump 34. This pump is connected throughcouplings 36 to an electrical drive motor 38.

The drive motor 38 includes a first shaft 40 connected to the coupling36 and a second oppositely extending shaft 42 connected to coupling 44.The coupling 44 is connected to hydraulic pump 46 which is in turnconnected through lines 48 and 50 to the other hydraulic motor 28.

A speed adjusting control 52 is attached to the variable displacementpump 34. This speed adjuster may include an appropriate manual controlso that the displacement of the pump 34 can be located at a desiredposition. With this arrangement, the hydraulic drive motor 26 willperform in a fixed fashion unless an adjustment is made by means of theconstruction 52.

The roll drive system described may be complemented by an electriccontroller 54 connected to the pump 46. The controller may be a nullsignal balance type as illustrated or any comparable type. Thecontroller is operated by the output of an electric signal comparator56. The comparator 56 is connected to a pair of roll position detectingdevices 58 and 60. The detector 58 is associated with the shaft 62 whichextends outwardly from, and is formed integrally with, the rollsupporting shaft 14. Similarly, the detector 60 is associated with theextension 64 of the shaft 16.

The detectors 58 and 60 may be of various types including positiontransducers, precision electrical tachometers, Selsyn motors and rotarydifferential transformers. In any event, the output from the detectorsis fed to the comparator 56 whereby the output of the comparator willdepend on any differences in the roll positions. If the roll positionsare synchronized, when the comparator output will be zero so that thecontroller 54 will not change the displacement of pump 46. Where therolls are out of synchronization, the comparator 56 will develop asignal proportional to the differences in position thereby causing thecontroller to make a proportional change in the displacement of pump 46.The adjustment will continue until the rolls return to propersynchronization.

FIG. 2 illustrates a modification of the roll drive means of theinvention. In this arrangement, the pumps 34 and 36 are each providedwith a separate electric motor 66 and 68. Where a roll synchronizationmeans is desired, the pumps could be controlled by the systemillustrated in FIG, 1 with the electric motors 66 and 68 operating atequal fixed speeds. On the other hand, detectors such as the detectors58 and 60 may be connected to a controller 70 for one of the electricmotors. By providing a variable speed electric motor, departures fromroll synchronization can be employed for developing a signal which willlead to a variation in the output of pump 34 to eventually accomplishand then maintain roll synchronization.

In the embodiment shown in FIG. 3, a single pump 72 and a singleelectric motor 74 are provided. The output from the pump 72 is dividedbetween the hydraulic motors 26 and 28. With this arrangement detectorssuch as shown at 58 and 60 may be associated with a by-pass valve 76connected between the pump and one of the hydraulic motors. Anydepartures from synchronization will proportionally control theoperation of this bypass valve thereby affecting the operation of thehydraulic motor 28. Again, the detecting and control means will operateto equalize and maintain the roll synchronization. The same results canbe achieved if the by-pass valve or a flow retarding valve is inserteddirectly in the line between pump 72 and hydraulic motor 28.

FIGS. 4 and illustrate one suitable detecting arrangement for achievingroll synchronization. In this arrangement, the shaft extensions 62 and64 are each provided with four equally spaced cams 78. The detectorsassociated with these shaft extensions comprise differentialtransformers 80 and 82. These transformers include reciprocally mountedarmatures 84 and 86 and the armatures are spring loaded so that the endsthereof will ride on the cam surfaces. As the shafts rotate, thepositions of the armatures relative to the transformer windings willvary thereby producing a varying electrical output signal.

The characteristics of the output signals are illustrated in FIG. 5. Asindicated, equal and opposite signals are produced by the respectivetransformers, and when the cams have the same alignment on each shaft,there will be no variation in the angular positions of the shafts andthe combined output will be zero.

The transformers are connected so that the individual outputs are ofopposite polarity. The respective signals are then bucked against oneanother in the manner shown or in a simple Wheatstone bridge circuit. Asignal will be generated whenever the respective outputs from thetransformers are not equal and opposite during every degree of rotationof the rolls. Any differential signal produced can then be fed to a nullbalance type of electrical controller which will produce a signal tomomentarily adjust the relative roll speeds until synchronization isachieved.

In the example illustrated, the signals vary between zero and I00percent in 45 of angular rotation, and the magnitude of any signal tothe controller will depend on the respective positions of the cams onthe roll shafts. A very accurate synchronization can be achieved. Thus,a typical system will have an accuracy of about two percent or less sothat the rolls can be kept in angular position synchronization withinO.9 of angular rotation. It will be appreciated that the number of camscan be varied and that other means can be employed for detecting therelative positions of the roll shafts and then using this informationfor providing momentary variations in roll speed.

As indicated, the output controller may be applied to one of the pumps,to an electric motor driving a pump, to a flow control valve, to aby-pass valve associated with one of the hydraulic drive motors, or toany other appropriate mechanism which will serve to synchronize the rolloperations.

In briquetting, double output shaft speed reducers are commonly used tominimize expense; however, this restricts the use of different rollsizes. The hydraulic systems described are much more compatible withchanges in roll sizes.

It has also been found that systems incorporating the teachings of thisinvention are highly efficient when compared with prior art systemsofthe type using speed reducers. Specially designed, double output,speed reducers are often required and these are relatively expensive.The concepts of this invention do not lead to excessive gear loading orgear wear or to other conditions which lead to deterioration of a drivesystem.

Where roll position detectors are utilized, the individual elementsemployed in the system are all of a relatively simple nature andelements such as the comparator, controller and adjuster structures arestandard items which, therefore, can be readily obtained.

It will be understood that various changes and modifications may be madein the above described construction which provide the characteristics ofthis invention without departing from the spirit thereof particularly asdefined in the following claims.

That which is claimed is:

1. In an apparatus for agglomerating particulate material including apair of agglomerating rolls defining mating material shaping portionsand means for feeding material between said rolls, the improvement indrive means for said rolls comprising a pair of hydraulic motors, eachof said motors being connected to a particular one of said rolls,hydraulic pump means connected to said hydraulic motors, and additionalmotor means for operating said pump means, means for setting the speedof one of said hydraulic motors, detecting means connected to at leastone of said rolls for determining the angular position thereof, andcontrol means connected to said detecting means, said control meansbeing connected to the other of said hydraulic motors for synchronizingthe angular position of said other hydraulic motor with the angularposition of said one hydraulic motor having the set speed.

2. An apparatus in accordance with claim 1 wherein said pump meansconsists of a pump attached to each hydraulic motor, a least one of saidpumps being of the variable displacement type, said one pump beingconnected to said other hydraulic motor and said control means operatingto vary the displacement of said one pump in response to the operationof said detecting means.

3. An apparatus in accordance with claim 1 including one pump connectedto both of said motors, and including a by-pass valve connected betweensaid pump and at least one of the hydraulic motors, said control meansoperating to control the flow of hydraulic fluid through said by-passvalve in response to the operation of said detecting means.

4. An apparatus in accordance with claim 2 wherein the motor meansdriving said pumps comprises a double shaft electric motor, saidelectric motor serving to drive both of said pumps.

5. An apparatus in accordance with claim 2 wherein said motor meanscomprises a separate electric motor for each of said pumps.

6. An apparatus in accordance with claim 1 wherein said pump meanscomprise a separate pump for each hydraulic motor, said motor meanscomprising a separate electric motor connected to the respective pumps,and wherein said control means are connected to at least one of saidelectric motors.

7. An apparatus in accordance with claim I wherein said indicating meanscomprise electrical signal generators connected to shafts carrying saidrolls whereby signalsare generated in accordance with the angularpositions of said rolls, said control means comprising a signalcomparator adapted to produce an output corresponding to the differencein angular positions of said rolls.

8. An apparatus in accordance with claim 7 wherein said electricalsignal generators comprise a pair of transformers each carrying amovable armature, a cam mounted on each of the shafts carrying saidrolls, the respective cams being engageable with the movable armaturesof said generators, said cams being of an identical configuration sothat movement of the armatures relative to the respective transformerwindings will be synchronized when said rolls are synchronized.

9. An apparatus in accordance with claim 1 including one pump connectedto both of said motors.

10. In an apparatus including a pair of rolls, and drive means for saidrolls, the improvement comprising detecting means connected to at leastone of said rolls for determining the angular position thereof, andcontrol means connected to said detecting means for synchronizing theangular positions of said rolls, said indicating means comprisingelectrical signal generators connected to shafts carrying said rollswhereby signals are generated in accordance with the angular positionsof said rolls, said control means comprising a signal comparator adaptedto produce an output corresponding to the difference in angularpositions of said rolls, said electrical signal generators comprising apair of transformers each carrying a movable armature, a cam mounted oneach of the shafts carrying said rolls, the respective cams beingengageable with the movable armatures of said generators, said camsbeing of an identical configuration so that movement of the armaturesrelative to the respective transformer windings will be synchronizedwhen said rolls are synchronized.

1. In an apparatus for agglomerating particulate material including apair of agglomerating rolls defining mating material shaping portionsand means for feeding material between said rolls, the improvement indrive means for said rolls comprising a pair of hydraulic motors, eachof said motors being connected to a particular one of said rolls,hydraulic pump means connected to said hydraulic motors, and additionalmotor means for operating said pump means, means for setting the speedof one of said hydraulic motors, detecting means connected to at leastone of said rolls for determining the angular position thereof, andcontrol means connected to said detecting means, said control meansbeing connected to the other of said hydraulic motors for synchronizingthe angular position of said other hydraulic motor with the angularposition of said one hydraulic motor having the set speed.
 2. Anapparatus in accordance with claim 1 wherein said pump means consists ofa pump attached to each hydraulic motor, at least one of said pumpsbeing of the variable displacement type, said one pump being connectedto said other hydraulic motor and said control means operating to varythe displacement of said one pump in response to the operation of saiddetecting means.
 3. An apparatus in accordance with claim 1 includingone pump connected to both of said motors, and including a by-pass valveconnected between said pumP and at least one of the hydraulic motors,said control means operating to control the flow of hydraulic fluidthrough said by-pass valve in response to the operation of saiddetecting means.
 4. An apparatus in accordance with claim 2 wherein themotor means driving said pumps comprises a double shaft electric motor,said electric motor serving to drive both of said pumps.
 5. An apparatusin accordance with claim 2 wherein said motor means comprises a separateelectric motor for each of said pumps.
 6. An apparatus in accordancewith claim 1 wherein said pump means comprise a separate pump for eachhydraulic motor, said motor means comprising a separate electric motorconnected to the respective pumps, and wherein said control means areconnected to at least one of said electric motors.
 7. An apparatus inaccordance with claim 1 wherein said indicating means compriseelectrical signal generators connected to shafts carrying said rollswhereby signals are generated in accordance with the angular positionsof said rolls, said control means comprising a signal comparator adaptedto produce an output corresponding to the difference in angularpositions of said rolls.
 8. An apparatus in accordance with claim 7wherein said electrical signal generators comprise a pair oftransformers each carrying a movable armature, a cam mounted on each ofthe shafts carrying said rolls, the respective cams being engageablewith the movable armatures of said generators, said cams being of anidentical configuration so that movement of the armatures relative tothe respective transformer windings will be synchronized when said rollsare synchronized.
 9. An apparatus in accordance with claim 1 includingone pump connected to both of said motors.
 10. In an apparatus includinga pair of rolls, and drive means for said rolls, the improvementcomprising detecting means connected to at least one of said rolls fordetermining the angular position thereof, and control means connected tosaid detecting means for synchronizing the angular positions of saidrolls, said indicating means comprising electrical signal generatorsconnected to shafts carrying said rolls whereby signals are generated inaccordance with the angular positions of said rolls, said control meanscomprising a signal comparator adapted to produce an outputcorresponding to the difference in angular positions of said rolls, saidelectrical signal generators comprising a pair of transformers eachcarrying a movable armature, a cam mounted on each of the shaftscarrying said rolls, the respective cams being engageable with themovable armatures of said generators, said cams being of an identicalconfiguration so that movement of the armatures relative to therespective transformer windings will be synchronized when said rolls aresynchronized.